1. Field of the Invention
The present invention generally relates to a window stay and, more particularly, to a framework for the support of a panel member such as a glass plate to make up window.
2. Prior Art
Windows, particularly those used in vehicles such as trains, automobiles or the like, have stringent requirements for fluid tightness to avoid possible intrusion of rain and/or dust; resistance to vibration; resistance to shock due to impingement of solids on the glass plate; and safety. In view of this, window stays generally employed nowadays comprise a metallic window frame which is secured to the wall structure and an elastic cushioning strip encircling the peripheral edge of the glass plate and held in position between the window frame and the glass retainer to avoid direct contact between the glass plate and either the window frame or the glass retainer. The elastic cushioning strip is either a strip made of elastic shock absorbing material or a strip made by drying or curing a filler-sealant which has been applied during the fabrication of the window. The compression of the strip sandwiched between the window frame and the glass retainer results in a reactive force tending to restore the strip to its original shape which provides both fluid tightness and vibration resistance.
One example of a prior art window stay so far found to be closest to the present invention is illustrated in FIG. 1 of the accompanying drawings.
FIG. 1 shows a cross-sectional representation of the prior art window stay taken in a direction generally perpendicular to the plane of the glass plate. The wall structure 1, for example, a double-paneled side wall of a train car, has a window frame 2 rigidly secured to it. An elastic cushioning strip 3 has a groove of a width generally equal to or slightly smaller than the thickness of the glass plate 4. The groove receives the glass plate 4. The elastic cushioning strip 3 is mounted in window frame 2 with its one side face held in contact with the peripheral flange 2a of window frame 2; and its other side in contact with the glass retainer 5 is secured to window frame 2 by means of a plurality of set screws 6 to press the peripheral edge of the glass plate 4 against the peripheral flange 2a. This prior art window stay is so designed that when the set screws 6 are tightened in the assembly described above, the elastic cushioning strip 3 is in a state of compression which exerts a reactive force tending to restore the elastic cushioning strip to its original shape. The effect of this reactive force is to tighten all contact seals permitting the window as a whole to exhibit fluid tightness, resistance to vibration and resistance to shock all at one time.
In the prior art window stay of the construction described above, the extent to which the elastic cushioning strip 3 is compressed depends on the extent to which the set screws 6 are tightened. Because of this, the set screws 6 used have to be of a type having a rigid and robust threaded shank; at the same time, the glass retainer 5 must have a relatively large cross-sectional area to withstand the reactive force. In addition, the set screws 6 must be placed at an angle relative to each other as shown in FIG. 1. Accordingly, a relatively large space is required for the mounting of the prior art window stay and the mounting procedures are complex.
These disadvantages and inconveniences in the prior art window stay exist because only the glass retainer 5 and the set screws 6 withstand the reactive force exerted by the compressed elastic cushioning strip 3. If one or more extra members were utilized in cooperation with the glass retainer 5 and the set screws 6 to withstand the reactive force, the above-described disadvantages and inconveniences would be obviated.
Furthermore, the prior art window stay under discussion makes use of the elastic cushioning strip 3 for the purpose of permitting the window stay as a whole to exhibit both the fluid tightness and shock absorbing properties. It has, however, been found that sole use of the elastic cushioning strip 3 is not effective in avoiding any possible separation from both the window frame 2 and the elastic cushioning strip 3 of fragments of the glass plate 4 when the latter has been cracked owing to, for example, collision with a stone. If fragments of the broken glass plate 4 separate, some train passengers seated adjacent to the window will be subjected to cuts and/or other accidents will occur. This dangerous possibility may be eliminated if the peripheral edge of the glass plate is bonded to the window frame 2 by the use of a bonding agent.
It is well known that vehicle front windows are generally subjected to a safety test during which they are struck by concrete blocks, one at a time. The requirements for passing this test include the provision that, even though the window glass cracks or is depressed, fragments of the broken window glass must not scatter into the interior of the vehicle. In anticipation of these safety requirements, it is not only necessary to improve the physical strength of each of the component parts of the glass window such as the glass plate and the window frame, but also to provide means for retaining the glass plate in the window frame and avoiding any separation between them. In other words, any relative movement between the glass plate and elastic cushioning strip must be substantially eliminated or minimized to keep the strip in tight contact with the peripheral edge of the glass plate. Then, even if the glass plate deforms as a result of being impacted by rigid foreign matter, the peripheral edge of the glass plate will stay in the window frame.
In spite of the foregoing consideration, the prior art window stay makes use of the elastic cushioning strip only for the purpose of providing fluid tightness and cushioning between the glass plate and the window frame, permitting relative slip between them to occur. Therefore, the prior art window stay has the disadvantages that the glass plate is insufficiently retained in the window frame and also in that the resistance to impact is low.